The invention is based on a hydraulic control arrangement which is used to operate a winch in easing, hoisting and mooring modes and which has an adjustable hydraulic motor (12) to drive the winch (10), a proportionally adjustable directional control valve (35), spring-centered in a mid position, to control the flow paths of a pressure medium between a pressure medium source (25), the hydraulic motor (12) and a pressure medium supply container (26), a pilot controller (65) which is used to control the adjustment of the directional control valve (35) and of the hydraulic motor (12) and has a control lever (81) which can be actuated as desired and can be deflected from a neutral position in one direction over a specific easing angle range (85) for easing at different speeds and can be deflected in the opposite direction over a specific hoisting angle range (86) for hoisting at different speeds, during a deflection of the control lever (81) over the entire hoisting angle range (86), the directional control valve (35) being fully opened and the hydraulic motor (12) being adjusted to a minimum absorption volume.
A hydraulic control arrangement of this type is disclosed by the typesheet RD 65 050/03.96 from the applicant. In such a control arrangement, the winch is preferably driven by an adjustable hydraulic motor. Using a directional control valve which is pilot-controlled, proportionally adjustable and spring-centered in a mid position, the flow paths of a pressure medium are controlled between a pressure medium source, the hydraulic motor and a pressure medium storage container. To control the adjustment of the directional control valve and of the hydraulic motor, use is made of a pilot controller having a control lever which can be actuated as desired and can be deflected from a neutral position in one direction over a specific easing angle range for easing at different speeds, and can be deflected in the opposite direction over a specific hoisting angle range for hoisting at different speeds. In the process, two adjustments are involved in changing the speed of the winch. Firstly, during a deflection of the control lever, the directional control valve is opened further and further, so that the amount of pressure medium flowing to the hydraulic motor is increased further and further. Secondly, the absorption volume of the hydraulic motor is reduced. It is conceivable to change the opening cross section of the directional control valve and the absorption volume of the hydraulic motor in parallel with each other. In the prior art, however, provision is made that, up to a pilot control pressure of 18 bar, for example, only the hydraulically pilot-controlled directional control valve is adjusted and, in the range of a pilot control pressure from 20 to 30 bar, for example, only the adjustable hydraulic motor is adjusted.
In the mooring mode, the hawser is to be kept under a predefinable tension. This tension can be set by means of the absorption volume of the hydraulic motor. In the prior art, the control lever of the pilot controller is deflected from a neutral position counter to the force of a restoring spring in one direction for the hoisting mode of the winch and in the other direction for the easing mode of the winch. For the mooring mode, which is generally intended to be maintained over a relatively long time period without the control lever being held in a specific position by hand, a fixing brake is provided for the control lever in the known hydraulic control arrangement, said brake holding the control lever within the hoisting angle range, counter to the force of the restoring spring, in a position corresponding to a specific absorption volume of the hydraulic motor.
In the case of the known hydraulic control arrangement, in the hoisting mode, the variable to be set, namely the speed of the hawser, becomes greater as the deflection angle of the control lever increases. In the mooring mode, the variable to be set is the torque exerted by the hydraulic motor. This torque decreases with increasing deflection angle of the control lever, a behavior which contradicts the usual concepts of setting a variable via a control lever, and can therefore lead to wrong setting. Another drawback of the known hydraulic control is that the hoisting mode and mooring mode cannot be distinguished by using the position of the control lever.
The invention is based on the object of constructing a hydraulic control arrangement which has the introductory-mentioned features in such a way that a type of mooring mode corresponding to the usual concept is possible.
In a hydraulic control having the introductory-mentioned features, according to the invention, the intended object is achieved wherein, the control lever, as viewed from the neutral position, can be deflected over a mooring angle range on the other side of the hoisting angle range, wherein and, with increasing deflection of the control lever in the mooring angle range, the hydraulic motor is adjusted in the direction of a greater absorption volume. Therefore, with increasing deflection of the control lever, the torque that can be exerted by the hydraulic motor increases, which corresponds to the usual concept of a control system and reduces the probability of wrong control. In addition, the angle range in which the control lever is located for hoisting and the angle range for the mooring mode are separated from each other, so that a reference to a different mode of operation can already be taken from the position of the control lever.
Thus according to another feature of the invention, during an adjustment of the control lever from the hoisting angle range into the mooring angle range a considerable rise in torque is preferably detectable, so that it is clearly pointed out to the operator that he is leaving the hoisting angle range with the control lever and passing into the mooring angle range.
As already outlined, a winch is often operated in the mooring mode over a relatively long time period, for example during the period during which a ship is lying in a harbor. In order that a person does not have to hold the control lever fixed during this entire time, provision is expediently also made in a control arrangement according to the invention as in the known hydraulic control arrangement, for the control lever to be capable of being brought into a position for the mooring mode from which it does not automatically return into the neutral position. The possibility of leaving the control lever in a specific position provides a temptation to operate a winch contrary to the regulations. This is because a person can use the mooring mode to haul in the hawser by the person first moving the control lever into a specific position in the mooring angle range and then attempting to do something at the hawser or at the load. It is therefore beneficial if, in the mooring mode, the speed with which the hawser can be hauled in is limited to a small value. According to a feature of the invention, a hydraulic control arrangement according to the invention is equipped with a nozzle and a second directional control valve for such a speed limitation, it being possible for this second directional control valve, at the transition of the control lever from the hoisting angle range to the mooring angle range, to be changed over into a mooring position in which the nozzle is located in the flow path of the pressure medium leading via the hydraulic motor, with the effect of limiting the rotational speed of the hydraulic motor to small values. Such a limitation on the rotational speed of the hydraulic motor is primarily advantageous for the direction of rotation in which the hawser is wound up. If a hawser breaks, for example in the mooring mode, then winding up takes place only at the limited speed so that the loose cable does not thrash about wildly in the surrounding area and endanger personnel. In addition, in the case of the winch being operated contrary to the regulations, during which operation a load is moved in the mooring mode, the speed is only low and therefore the hazard to personnel is low.
According to other features of the invention, the nozzle and the second directional control valve are preferably arranged in series with each other and in a bypass line to the first directional control valve, the first directional control valve, at the transition of the control lever from the hoisting angle range to the mooring angle range, being brought into a mid position in which the feed of pressure medium to the hydraulic motor under pressure is blocked by the first directional control valve. It is intrinsically also conceivable to arrange the parallel circuit of a nozzle and of the second directional control valve in series with the first directional control valve. The second directional control valve would then be completely open in the hoisting mode and closed in the mooring mode. However, it would have to be designed for the maximum quantity of pressure medium flowing to the hydraulic motor and to be dimensioned to be accordingly large. By contrast, in the case of a construction according to features of the invention, the second directional control valve can be relatively small.
According to FIG. 5, the pilot controller is a hydraulic pilot controller and the first directional control valve can be actuated hydraulically. As a result, in the event of an adjustment of the control lever into the mooring angle range, said first directional control valve is moved into its mid position by both pilot control chambers being acted on with the same pilot control pressure, also present on the hydraulic motor. This simplifies the control arrangement as compared with a different solution, in which, in order to return the first directional control valve into the mid position, its two pilot control chambers are relieved of pressure. This is because the two control lines leading from the pilot controller to the first directional control valve are usually also connected to the two inputs of a changeover valve, from the output of which a control line leads to the adjusting device of the hydraulic motor. Via the changeover valve, a pilot control pressure present in the one pilot control chamber or in the other pilot control chamber of the first directional control valve is supplied to the adjusting device of the hydraulic motor. If it were then desired to relieve the two pilot control chambers of the directional control valve to the tank, then the second directional control valve would have to be used to separate the input of the changeover valve on which a pilot control pressure for the hydraulic motor prevails in the hoisting mode, from the corresponding pilot control chamber of the directional control valve, and the pilot control chambers could be relieved separately to the tank. This would make a tank connection on the directional control valve and a tank duct necessary. Particularly advantageous in this case is the construction according to further features of the invention if, the pilot controller comprises an adjustable pilot valve with a pilot control pressure connection which can be connected to various pilot control chambers of the first directional control valve via a directional control valve that is operated by the deflection of the control lever. A pilot controller with a pilot valve whose pilot control pressure connection can be connected via a directional control valve to one or the other pilot control chamber of a proportionally adjustable directional control valve provides the advantage that the behavior of the pilot control is not influenced in a different way by tolerances in the pilot valve, irrespective of the direction in which the control lever is deflected from its neutral position. If, therefore, for example the pilot control valve is in each case actuated in the same way as a function of the angle, irrespective of the direction, during a deflection of the control lever from the neutral position then, in the event of the same deflection angle, the pilot control pressures are also equal. When the pilot valve is set, the pilot control pressure in the two deflection directions are influenced in the same way.
For load-independent control of the rotational speed of a winch, a feed metering diaphragm of the proportionally adjustable directional control valve is assigned a pressure compensator that maintains a fixed pressure difference across the feed metering diaphragm. The bypass line then advantageously circumvents both the pressure compensator and the directional control valve. One control side of the pressure compensator can then be connected in a straightforward way to a connection of the directional control valve, via which a brake on the winch can have pressure applied to it and which, in the mid position of the directional control valve, is relieved of pressure in order that the brake can engage. However, it is also conceivable to connect one control side of the pressure compensator via a changeover valve to one or the other connection of the hydraulic motor and to permit the bypass line to branch off downstream of the pressure compensator, so that only the directional control valve is circumvented. The pressure compensator and nozzle in the bypass line then together form a flow control valve, so that in the mooring mode, one has flow regulation for the pressure medium flowing from the pressure medium source to the hydraulic motor.
In the bypass line, according to features of the invention, there is advantageously a nonreturn valve, which opens in the direction of the flow of pressure medium from the pressure medium source to the hydraulic motor. In addition, there is a pressure limiting valve, which is arranged between the two connections of the hydraulic motor and by means of which the pressure of the connection of the hydraulic motor to which pressure is applied in the mooring mode is limited to a maximum value. When the cable is being let out in the mooring mode, pressure medium flows from the connection of the hydraulic motor to which pressure is applied to the other connection on a short path, via the pressure limiting valve. The hydraulic motor does not have to take up a large quantity of pressure medium via long lines, which would be associated with the risk of cavitation. If the control pressure is supplied internally via a pressure reducing valve, then the latter is connected by its pressure connection to the bypass line, specifically upstream of the nozzle, according to features of the invention the nonreturn valve being arranged between the pressure connection and the pressure medium source.
In the known hydraulic control arrangement for a winch, a hydraulically vented mechanical brake is supplied with pressure medium via a changeover valve from the two motor valve connections of the proportionally adjustable directional control valve. In the mid position of the directional control valve, both motor valve connections of the directional control valve, and therefore also the brake, are relieved to the tank, so that the brake can engage. In accordance with the construction according to features of the invention, the proportionally adjustable directional control valve is in its mid position in the mooring mode, the intention being for a supply of pressure medium to the hydraulic motor to be possible via the bypass line, and therefore one motor valve connection of the proportional directional control valve is advantageously not relieved to the tank when in its mid position, in order not to need a further valve between this motor valve connection and the branch point of the bypass line. According to further features of the invention, therefore, in the mooring mode, the brake is advantageously supplied with pressure medium via the second directional control valve and can also be relieved of pressure via the second directional control valve when the control lever is put into its neutral position. It is therefore essential here that the hydraulic brake actuator can have pressure applied to it and can be relieved of pressure in the mid position of the proportional directional control valve, independently of the latter.
As in the prior art, according to features of the invention, there is a nonreturn device for the control lever, which comprises a restoring spring which, in the easing and hoisting angle range, is prestressed to a greater extent as the deflection of the control lever increases, so that in the aforementioned angle ranges, a restoring force is exerted on the control lever. Adjusting the control lever in the mooring angle range, on the other hand, is indifferent with regard to the prestressing of the restoring spring. Therefore, in the mooring angle range, the latter does not exert any restoring force on the control lever either. This renders a separate fixing brake for the control lever superfluous. Advantageous refinements of the restoring device, referring to the presence and absence of a restoring force, and a cam disk which is coupled to the control lever so as to be secure against rotation and collaborates with the restoring spring are provided. Here, reference is made in particular to the configuration according to features of the invention, according to which, in the mooring angle range, a pressure piece of the restoring device is pressed against the cam disk by a second spring in addition to the restoring spring. This increases the frictional force between the pressure piece and the cam disk, so that a small torque exerted on the control lever by a pilot valve certainly does not lead to any adjustment of the control lever.
The hydraulic control arrangement according to the invention is used for the purpose of operating a winch in the easing, hoisting and mooring mode. For many winches, however, no mooring mode is envisaged. In order to be able to use the same components in the pilot controller as those for a winch with a mooring mode, in the development of a hydraulic control arrangement according to the invention and according to further features of the invention, provision is made for the deflection of the control lever at the end of the easing angle range and at the end of the mooring angle range in each case to be limited by a stop face on a part that corotates with the control lever, and an opposing stop, and for the pressure piece to have an additional stop which, depending on the type of installation of the pressure piece and/or of an opposing stop, limits the path of the pressure piece in the direction of more intensive prestressing of the restoring spring at the end of the hoisting angle range (winch without mooring mode) or does not limit the same (winch with mooring mode).